1) The Mishna in Kelim (1:6) writes that Eretz Yisrael has greater kedusha than all other lands because bikurim, shtei ha'lechem, and the omer can only be brought from Eretz Yisrael. Why should the Mishna have seized on only these examples to illustrate kedushas ha'aretz? Why not refer to any of the mitzvos ha'teluyos ba'aretz that only apply in Eretz Yisrael?
R' Soloveitchik explains that there are 2 dinim in kedushas ha'aretz: 1) sanctity of the land itself, which creates the chiyuvim of mitzvos ha'teluyos ba'aretz; 2) sanctity of the land that is a function of it being the makom ha'mikdash.
The Mishna is speaking about kedushas ha'aretz which is a function of the land being an extension of the mikdash. Therefore, it refers only to those items which grow in the land and are brought to the mikdash as an offering.
This explains why that although the Rambam paskens that eiver ha'yarden is chayav m'd'oraysa in terumos u'maasros (Terumos 1:6, Mishne l'Melech ch 4), he paskens (Bikurim 2:1) that the chiyuv to bring bikurim from eiver ha'yarden is only derabbanan. Eiver ha'yarden has kedushas ha'aretz with respect to mitzvos ha'teluyos ba'aretz, but lacks the kedusha of being an extension of the mikdash.
Rav Wahrman in his She'eiris Yosef (vol 2 siman 26) uses this yesod to answer Tos question as to why the gemara (Baba Basra 81) needs a special derasha of "b'artzecha" to teach us that bikurim applies only in Eretz Yisrael. Why is that not implicit in its being a mitzvah ha'teluya ba'aretz? He suggests that since bikurim is connected not to the kedusha of the land in and of itself, but rather to the mikdash, therefore it does not fall under the same umbrella of the other mitzvos ha'teluyos ba'aretz and we need a new limud.
(One wrinkle in all this is that the Rambam Shemita 4:28 paskens that shemita does not apply m'doraysa in eiver ha'yarden. Rav Wahrman works out a connection between shemita and mikdash -- ayen sham.)
"V'haya ki savo el ha'aretz..." -- "ain v'haya elah lashom simcha." Coming to Eretz Yisrael, coming to bask in the kedushas ha'aretz, is the greatest simcha, a taste of the simcha of geulah, "az yimalei sechok pinu." (Ohr haChaim). Ashrei doreinu that we have such an opportunity.
2) "...Nisativ la'ger la'yason v'la'almanah... lo avarti m'mitzvosecha v'lo shachachti." Klal Yisrael knows how to open their pocketbooks and give. There was recently a tragedy in the community where a women passed away and left a family with young children and there was immediately an effort to raise a substantial sum to help them. We all do a tremendous job of jumping in to help when people need it.
But what happens in a month? How many people will remember that family and those children? How many people will think of them in a year? In 5 years?
When the needs of the ger, yasom, or almanah are staring us in the face on yeshivaworld or some other place, it tugs at the heart strings. But that's not all the Torah wants. "V'lo shachachti!" I didn't forget about them! The empathy didn't fade away a week, a month, a year, later. It wasn't out of sight, out of mind. (based on the Mishnas Sachir)